System and Method for Determining Parking Infraction

ABSTRACT

Various embodiments are described herein for methods and systems for managing a parking area. In one embodiment, the method comprises receiving a parking authorization request from a parking lot user, the request specifying a parking stall identifier corresponding to a parking stall occupied by the user&#39;s vehicle, the request further specifying a parking duration parameter identifying a time duration the user&#39;s vehicle can occupy the stall; determining a parking duration rule for the stall based on the parking duration parameter, the rule indicating a parking expiration time; at a first time, receiving a first data associated with the parking stall identifier, the first data comprising an occupancy parameter indicating a presence or absence of a parked vehicle at the identified stall; if the occupancy parameter indicates a presence of a parked vehicle, generate a citation alert for the stall if the first time exceeds the parking expiration time.

TECHNICAL FIELD

The invention relates generally to the field of parking enforcement, andmore specifically to systems and methods for the automatic detection ofparking infractions.

BACKGROUND

Regulation of vehicle parking in parking lots and street allows for amore orderly flow of traffic and parking resource management at varioustimes of the day or week. This further encourages vehicle turnover andbetter and fairer utilization of parking resources. Implementation ofparking regulations further allows the parking authority responsible formanaging the use of parking spaces to generate revenue through thecollection of fees.

One of the concerns associated with management of fee-for-use parkinglots is unauthorized use of such parking lots. Typically, a parkingenforcement officer manually monitors such fee-for-use parking lots todetect unauthorized use of parking spaces. However, the parkingenforcement officer is usually required to patrol the parking lots onfoot and issue citations to unauthorized vehicles. Such a process tendsto be slow, expensive, prone to errors and interruption due to inclementweather, safety issues, fatigue or other issues related to more manualmethods of enforcement.

SUMMARY

In a broad aspect, at least one embodiment described herein provides amethod of managing a parking area, the parking lot comprising aplurality of parking stalls for occupancy by a plurality of vehicles,each parking stall being uniquely identifiable using a parking stallidentifier. The method comprises: receiving a parking authorizationrequest from a parking lot user, the parking authorization requestspecifying a parking stall identifier corresponding to a parking stallthat is occupied by a vehicle belonging to the parking lot user, theparking authorization request further specifying a parking durationparameter identifying a duration of time for which the parking lot usercan park the vehicle at the parking stall; determining a parkingduration rule for the parking stall based on the parking durationparameter, the parking duration rule indicating a parking expirationtime at which the vehicle must vacate; at a first time, receiving afirst data associated with the parking stall identifier, the first datacomprising an occupancy parameter indicating a presence or an absence ofa parked vehicle at the parking stall identified by the parking stallidentifier; if the occupancy parameter indicates a presence of a parkedvehicle, determining if the first time exceeds the parking expirationtime; and if the first time exceeds the parking expiration time,generating a citation alert for the parking stall identified by theparking stall identifier.

In some embodiments, the method of managing a parking area furthercomprises issuing a parking citation to the parked vehicle based on thecitation alert.

In some embodiments, the parking authorization request further comprisesa vehicle identifier identifying at least one characteristic of thevehicle, the method comprising at the first time, further receiving adetected vehicle identifier corresponding to at least one detectedcharacteristic of the parked vehicle at the parking stall, the at leastone detected characteristic being comparable to the at least onecharacteristic; determining if the parked vehicle is the same as thevehicle corresponding to the parking authorization request by comparingthe vehicle identifier and the detected vehicle identifier; if theparked vehicle and the vehicle corresponding to the parkingauthorization request are determined to be different vehicles,determining if a second parking authorization request is received fromthe parked vehicle; and if the second parking authorization request isdetermined to not have been received from the parked vehicle, generatingthe citation alert for the parking stall.

In some embodiments, the at least one characteristic of the vehiclecomprises a data item selected from the group consisting of a licenseplate number of the vehicle, year of make of the vehicle, model of thevehicle, color of the vehicle and transponder identity of the vehicle.

In some embodiments, the at least one detected characteristic of theparked vehicle comprises a data item selected from the group consistingof a license plate number of the vehicle, model of the vehicle, color ofthe vehicle, shape and length of the vehicle, and transponder identityof the vehicle.

In some embodiments, the first time does not exceed the parkingexpiration time, and the first data further comprises a first detectedvehicle identifier identifying at least one characteristic of the parkedvehicle detected at the first time, and wherein the method furthercomprises: at a second time, where the second time does not exceed theparking expiration time, receiving a second data associated with theparking stall identifier, wherein the second data comprises a seconddetected vehicle identifier identifying at least one characteristic of aparked vehicle detected at the parking stall at the second time, whereinthe second time is subsequent to the first time, and wherein the atleast one characteristic of the parked vehicle detected at the firsttime and the at least one characteristic of the parked vehicle detectedat the second time correspond to a same data item; comparing the firstdetected vehicle identifier to the second detected vehicle identifier;if the first detected vehicle identifier and the second detected vehicleidentifier are determined to correspond to different vehicles,determining if a second parking authorization request is received fromthe parked vehicle detected at the second time; and if the secondparking authorization request is determined to not have been received,generating the citation alert for the parking stall.

In another aspect, in at least one embodiment described herein, there isprovided a method of managing a parking lot using a patrol vehicle, theparking lot comprising a plurality of parking stalls for occupancy by aplurality of vehicles, each parking stall being uniquely identifiableusing a parking stall identifier. The method comprises operating thepatrol vehicle to patrol the parking lot; determining, at a first time,for an occupied parking stall, a parking stall identifier; determining,at the first time, a parking duration rule for the parking stallidentifier based on a parking authorization request comprising a parkingduration parameter received from an operator of a vehicle occupying theoccupied parking stall, wherein the parking duration parameteridentifies a duration of time for which the vehicle can be parked at theparking stall, and wherein the parking duration rule indicates a parkingexpiration time at which the vehicle must vacate the parking stall; anddetermining if the first time exceeds the parking expiration time, andif so, generating a citation alert for the parking stall identified bythe parking stall identifier.

In some embodiments, the method of managing a parking lot using a patrolvehicle further comprises issuing a parking citation to a parked vehiclebased on the citation alert.

In some embodiments, the first time does not exceed the parkingexpiration time, the method of managing a parking lot using a patrolvehicle further comprises determining, at the first time, a detectedvehicle identifier corresponding to at least one detected characteristicof a parked vehicle at the parking stall; determining if the parkedvehicle corresponds to the vehicle associated with the parkingauthorization request, wherein the parking authorization request furthercomprises a vehicle identifier identifying at least one characteristicof the vehicle; if the parked vehicle does not correspond to the vehicleassociated with the parking authorization request, determining if asecond parking authorization request is received for the parking stallidentifier; and if the second parking authorization request isdetermined to not have been received for the parking stall identifier,generating the citation alert and issuing the parking citation to theparked vehicle.

In some embodiments, the parking lot is patrolled based on aprescheduled time.

In some embodiments, determining the parking stall identifier comprisescapturing one or more images of the occupied parking stall using animage detector mounted on the patrol vehicle; and processing the one ormore images to identify the parking stall identifier.

In some embodiments, processing the one or more images comprisesconverting the one or more images into a machine-encoded text.

In some embodiments, the parking stall identifier is designed tominimize blooming.

In some embodiments, determining the parking stall identifier comprisesscanning the occupied parking stall using a radio-frequencyidentification reader mounted on the patrol vehicle, wherein the parkingstall identifier comprises a radio-frequency identification tagdetectable by the radio-frequency identification reader.

In some embodiments, determining the parking stall identifier comprisesidentifying the GPS coordinates corresponding to the occupied parkingstall being patrolled and determining an associated parking stallidentifier by querying a parking management database.

In some embodiments, identifying an occupied parking stall in theparking lot comprises scanning each parking stall within the parking lotto capture one or more images of the parking stall; and processing theone or more images to detect absence or presence of a vehicle in theparking stall.

In some embodiments, determining the detected vehicle identifiercomprises detecting a license plate number of the parked vehicle usingan image detector.

In another aspect, in at least one embodiment described herein, there isprovided a parking lot management system for a parking lot comprising aplurality of parking stalls for occupancy by a plurality of vehicles,each parking stall being uniquely identifiable using a parking stallidentifier, the system comprising a communication network; anon-transient computer memory; and at least processor coupled to thenon-transient computer memory and the communication network. The atleast one processor being configured to i) receive a parkingauthorization request from a parking lot user, the parking authorizationrequest specifying a parking stall identifier corresponding to a parkingstall that is occupied by a vehicle belonging to the parking lot user,the parking authorization request further specifying a parking durationparameter identifying a duration of time for which the parking lot usercan park the vehicle at the parking stall; ii) determine a parkingduration rule for the parking stall based on the parking durationparameter, the parking duration rule indicating a parking expirationtime at which the vehicle must vacate; iii) at a first time, receive afirst data associated with the parking stall identifier, the first datacomprising an occupancy parameter indicating a presence or an absence ofa parked vehicle at the parking stall identified by the parking stallidentifier; iv) if the occupancy parameter indicates a presence of aparked vehicle, determine if the first time exceeds the parkingexpiration time; and v) if the first time exceeds the parking expirationtime, generate a citation alert for the parking stall identified by theparking stall identifier.

In some embodiments, the processor is further configured to perform themethod described in the preceding paragraphs.

In another aspect, in at least one embodiment described herein, there isprovided a computer-readable medium storing computer-executableinstructions. The instructions cause a processor to perform a method ofmanaging a parking area, the parking area comprising a plurality ofparking stalls for occupancy by a plurality of vehicles, each parkingstall being uniquely identifiable using a parking stall identifier. Themethod comprises receiving a parking authorization request from aparking lot user, the parking authorization request specifying a parkingstall identifier corresponding to a parking stall that is occupied by avehicle belonging to the parking lot user, the parking authorizationrequest further specifying a parking duration parameter identifying aduration of time for which the parking lot user can park the vehicle atthe parking stall; determining a parking duration rule for the parkingstall based on the parking duration parameter, the parking duration ruleindicating a parking expiration time at which the vehicle must vacate;at a first time, receiving a first data associated with the parkingstall identifier, the first data comprising an occupancy parameterindicating a presence or an absence of a parked vehicle at the parkingstall identified by the parking stall identifier; if the occupancyparameter indicates a presence of a parked vehicle, determining if thefirst time exceeds the parking expiration time; and if the first timeexceeds the parking expiration time, generating a citation alert for theparking stall identified by the parking stall identifier.

Other features and advantages of the present application will becomeapparent from the following detailed description taken together with theaccompanying drawings. It should be understood, however, that thedetailed description and the specific examples, while indicatingpreferred embodiments of the application, are given by way ofillustration only, since various changes and modifications within thespirit and scope of the application will become apparent to thoseskilled in the art from this detailed description.

BRIEF DESCRIPTION OF THE DRAWINGS

Several embodiments of the present invention will now be described indetail with reference to the drawings, in which:

FIG. 1 is a block diagram of a parking lot in accordance with an exampleembodiment;

FIGS. 2A-2C is a block diagram of various parking stall configurationsin accordance with an example embodiment;

FIG. 3 is a block diagram depicting a mobile enforcement vehicle onpatrol in accordance with an example embodiment;

FIG. 4 is a block diagram illustrates determining the position of aparked vehicle in accordance with an example embodiment;

FIG. 5 is a block diagram depicting the structure of a parkingmanagement database in accordance with an example embodiment;

FIGS. 6A-6B is a process flow diagram for pay-by-space enforcement inaccordance with an example embodiment;

FIGS. 7A-7B is a process flow diagram for pay-by-space enforcement usinglicense plate information in accordance with an example embodiment;

FIGS. 8A-8B is another process flow diagram for pay-by-space enforcementusing license plate information in accordance with another exampleembodiment; and

FIGS. 9A-9B is a process flow diagram for pay-by-space enforcement usingvoucher identification numbers in accordance with an example embodiment.

The drawings are provided for the purposes of illustrating variousaspects and features of the example embodiments described herein. Forsimplicity and clarity of illustration, elements shown in the FIGS. havenot necessarily been drawn to scale. Further, where consideredappropriate, reference numerals may be repeated among the FIGS. toindicate corresponding or analogous elements.

DETAILED DESCRIPTION

It will be appreciated that numerous specific details are set forth inorder to provide a thorough understanding of the example embodimentsdescribed herein. However, it will be understood by those of ordinaryskill in the art that the embodiments described herein may be practicedwithout these specific details. In other instances, well-known methods,procedures and components have not been described in detail so as not toobscure the embodiments described herein.

The embodiments of the systems and methods described herein may beimplemented in hardware or software, or a combination of both. Theseembodiments may be implemented in computer programs executing onprogrammable computers, each computer including at least one processor,a data storage system (including volatile memory or non-volatile memoryor other data storage elements or a combination thereof), and at leastone communication interface. For example, and without limitation, thevarious programmable computers may be a server, network appliance,set-top box, embedded device, computer expansion module, personalcomputer, laptop, mobile telephone, smartphone or any other computingdevice capable of being configured to carry out the methods describedherein.

Each program may be implemented in one or a multiplicity of languagesincluding high level procedural or object oriented programming orscripting language, assembler, macro or other programmatic methods tocommunicate with a computer system. The language may be a compiled orinterpreted language. Each such computer program may be stored locallyon a non-transitory computer readable storage medium (e.g. read-onlymemory, magnetic disk, optical disc) or remotely as on a remote server,such as on a third party cloud server or on the internet generally. Theremotely stored programs may be accessed via a local communicationsystem. The storage medium and/or the local or remote servers soconfigured cause a computer to operate in a specific and predefinedmanner to perform the functions described herein.

While particular combinations of various functions and features areexpressly described herein, other combinations of these features andfunctions are possible that are not limited by the particular examplesdisclosed herein, and these are expressly incorporated within the scopeof the present invention.

As the term module is used in the description of the variousembodiments, a module includes a functional block that is implemented inhardware or software, or both, that performs one or more functions suchas the processing of an input signal to produce an output signal. Asused herein, a module may contain sub-modules that themselves aremodules.

The various embodiments described herein generally relate to methods andsystems for pay-by-space parking. Pay-by-space parking is one system ofparking management which permits regulation of parking areas or parkingstalls on an individualized basis. A parking area may have one or moreparking stalls, where each parking stall may be identified or labeledwith a unique parking stall number. For the purpose of this disclosure,a “parking area” may refer to any location having one or more spaces inwhich a vehicle can be parked. Parking areas therefore include parkingstalls within parking structures, underground parking lots, ground levelparking lots and road-side parking.

A motorist wishing to park his or her vehicle in one of the unoccupiedparking stalls (a “parker”) pays a fee associated with occupying thatparking stall for a fixed period of time and is generally required tovacate the parking stall when that period of time has lapsed.Alternatively parking policy may permit the parker to repay (i.e.extend) their parking session. The parker's failure to vacate theparking stall on time may constitute a parking violation for which aparking citation may be issued by the parking authority responsible formanaging the parking area.

In the pay-by-space parking regime, the parker generally first parks hisor her car at a desired parking stall and then pays the necessaryparking fee for the use of that particular parking stall. In most cases,the parker only specifies the duration of time for which the parkerdesires to occupy the parking stall. In some other cases, the parkeradditionally specifies to the parking authority the parking stall numberthat is being occupied. The parking authority may provide parking metersfor each parking stall to collect payment. The parking authority mayalternatively provide a parking kiosk for a group of parking stalls forparkers to specify the parking stall being used and provide payment.Additionally, in some cases, the parking authority may also acceptparking stall information and payment using mobile phone or smartphoneor by web technologies. The parking fee may be set by the parkingauthority, and various fee structures may be imposed. For example, theparking authority can choose to charge the parker on a fixed fee basis,such a flat-rate parking fee, or on a variable fee basis in which thefee may be based on the amount of parking time desired. In some othercases, additional parking arrangements may be established between theparker and the parking authority. For example, the parker and theparking authority may enter into a parking subscription arrangement sothat the parker may be able to occupy a designated stall each time theparking lot is used. The subscription may provide an agreement betweenthe parker and the parking authority with respect to times and datesduring which the designated parking stall may be used and the method ofpayment (e.g. bi-weekly, monthly etc.).

Reference is first made to FIG. 1, which illustrates a block diagram ofa parking lot 100 according to an example embodiment. As illustrated,parking lot 100 includes numerous parking stalls 105 of more or less thesame dimensions. Each parking stall 105 may be legally occupied by aparker's vehicle 120 as long as the parker obeys the conditionsassociated with the particular parking stall and the parking lotoverall.

In the illustrated embodiment, the parking lot 100 is a paid parking lotwhere a parker is required to make a payment in order to occupy aparking stall 105. Typically, the payment required is proportional tothe duration of time for which the parker desires to park the vehicle.In some other cases, however, the payment required may be a fixedpayment. In some cases the use of the parking lot 100 may be subject tothe terms of a predefined contract or subscription, including those thatspecify times, durations and the identity of the vehicle or vehiclespermitted to use the parking lot 100.

The parking lot 100 and accordingly, the parking stalls 105 may belocated completely outdoors, completely indoors or partly outdoors andindoors. For example, in some cases, the parking lot 100 may be providedalong a roadway 110 upon which vehicles 120 may be driven. The termroadway 110 may be used to refer to any transportation route upon whicha vehicle 120 may be driven and parked. In another example, the parkinglot 100 may be established in an enclosed area, such as an undergroundparking structure.

Parking meters 160 or kiosks (not shown) may be provided for the purposeof collecting parking fees. Individualized parking meters 160 locatedbeside each parking stall 140 may be provided to allow the parker to payfor the associated stall. Alternatively, a single parking kioskconfigured with the necessary input and interface functionalities may beused to collect fees for a number of parking stalls. Such a kiosk can belocated in proximity to the parking stalls that it serves to allowparkers to purchase parking time. In the case of a parking kioskconfigured to serve several parking stalls, the parker may be requiredto enter the parking stall number to indicate the stall being used.

When a parker pays for a parking stall, the payment information, stallinformation and the time of payment may be sent to a central processoras a parking request for processing and recorded in a parking managementdatabase (“database”). Upon receipt of a parking request, the centralprocessor may update the status of the relevant parking stall toindicate that the respective parking stall is occupied. Other stallrelated information such as the parking expiration time for that stallmay also be updated. In some embodiments of the present invention, theinformation contained in the parking request may be received andprocessed in real time. In other embodiments, the parking requests maybe received and processed in batches at a central location (such as, forexample, the parking office). The latter case may apply, for instance,where there is a delay or an interruption preventing the parking kioskor parking meter from communicating the parking requests to the centralprocessor. The parking kiosk or parking meter may continue to collectpayments and accept parking requests while the communication delay orinterruption persists, and transmit all unsent parking requests to thecentral processor once communication is re-established.

In some cases, post processing of batched data also permits correctionof errors by parkers (when entering their stall number or license numberfor example) and providing grace periods before and after the parkingsession ends. Additionally post processing facilitates patrollingefficiency since the patrol vehicle does not have to stop to issue aninfraction every time a parking violation is detected. Post processingand associated advantages are discussed in further detail below.

The parking kiosk or parking meter may issue a receipt or a parkingvoucher to the parker indicating the amount paid and the parkingexpiration time. The parker may choose to place the voucher for displayon the dashboard or keep the ticket. In some embodiments, placement ofthe parking voucher on the dashboard may be optional since the databasehas a record of when a parking stall should be occupied and when itshould be vacated based on the information obtained from the parkingrequest.

Preparation of Parking Stalls

With respect to the parking stalls, each parking stall is labelled witha unique parking stall number before being used. The database may beused by the central processor to store all relevant informationregarding each parking stall within the parking area. In someembodiments, the database may be integrated with the central processor.In other embodiments, the database may be independent or separated fromthe central processor. In this case, the database may be anetwork-accessible database that may be accessed over a communicationsnetwork.

Reference is now made to FIGS. 2A-2C which illustrates different parkingstall configurations, each configuration having parking stall labelledwith a parking stall number 210. The term parking stall number usedherein may be any unique identifier capable of identifying a parkingstall. Therefore, a stall number may be a numeric or alphanumericidentifier.

Each parking stall in the various embodiments herein is demarcated fromneighbouring parking stalls. This may be accomplished by using one ormore demarcation lines 220 indicated on the surface of the ground. Insome other cases, different colors may be used to distinguish betweendifferent parking stalls. For instance, alternate parking stalls may becolored using the same color to distinguish the parking stalls. In someother cases, physical barriers may be used to distinguish betweenparking stalls.

FIG. 2A illustrates angled parking stalls 200A, while FIG. 2Billustrates parallel parking stalls 200B. Lastly, FIG. 2C illustratesrectangular parking stalls 200C. As shown in FIGS. 2A-2C, the parkingstall number 210 may be indicated using markings on the ground. Forexample, the five angled parking stalls 200A may be labeled “A1” to“A5”. In other embodiments, parking stall signs may be used tofacilitate identification of the parking stall number.

The locations of each parking stall can be further identified using anumber of location markers such as GPS coordinate points 230 to specifythe four corners of each parking stall. These location markers mayassist a mobile enforcement vehicle, discussed below, to identifyindividual parking stalls. Alternatively, a single location marker suchas a GPS coordinate point corresponding to the center of the stall (notshown) may be used instead. The latter method may be less precise inrespect of determining the boundaries of a parking stall since theparking stalls may not be of standard dimensions, making demarcation ofindividual stalls more difficult by the mobile enforcement vehicle.

A survey of the parking area may also be performed prior to its use toobtain accurate positional information (i.e. GPS coordinates of eachcorner) for the parking stalls. The survey data may be stored in amachine readable format such as XML, KML or CSV. Additionally, referenceimages of empty stalls may additionally be obtained in association witheach stall to indicate a field of view in which the parking stall isempty to facilitate identification of the correct parking stall.

Management of Pay-by-Space Parking

In the pay-by-space system, each occupied parking stall may have adifferent parking expiration time. In other words, each parking stallmay be governed by its own set of parking enforcement rules. To ensure aparker's compliance with parking enforcement rules, parking enforcementofficers (“PEO”) may be relied upon. The PEO may patrol the parking areaaccording to a desired patrol schedule and patrol route. In someembodiments, the patrol schedule may require that PEO patrol the parkingarea continuously, at a predetermined time interval, or as required bythe parking authority. In other embodiments the patrol schedule andpatrol route may be based on various historical statistics. For example,parking stalls that are associated with higher instances of parkinginfractions may justify more frequent patrols. In yet other embodiments,to improve efficiency, parking stalls that are empty may be ignored bythe PEO, while parking stalls that are occupied may be examined orscanned. During a scan, the parking stall number or informationpertaining to the vehicle occupying the stall, or both may be recordedby the PEO.

Traditionally, enforcement of pay-by-space parking by PEOs has oftenbeen performed on foot using a handheld device such as a camera-equippedsmartphone or a dedicated specialized handheld device. This so-called“handheld enforcement” generally requires the PEO to patrol the parkingarea or parking lot on foot and scan each vehicle and the stall in whichvehicle occupies one by one. Where a citation is to be issued, the PEOmay issue the citation by printing the citation and placing the citation(i.e. serving the citation) on the windshield of the parked vehicle. Inother circumstances, the PEO may make note of all parking stalls inwhich citations ought to be issued and transmit the information to thecentral processor at a later time for batch processing and subsequentlymailed out to the parker.

It can be appreciated that enforcement by a walking PEO using a handhelddevice is time consuming. Therefore, it may be preferable to patrolusing vehicular mobile enforcement techniques (i.e. mobile enforcementvehicle). A mobile enforcement vehicle equipped with the appropriatescanning systems may scan and collect parking stall information at amuch higher speed. The mobile enforcement vehicle may also transmitvehicle and stall information in real time or in batch-mode. Vehiclesfor which citations are required may be determined immediately and acitation may be generated immediately (i.e. issuance of citations inreal-time) or mailed in batches at a later time (i.e. issuance ofcitations in batch mode). Alternatively, parking stall numbers for whicha citation ought to be issued may be transmitted to an on-foot PEO whomay then go directly to the citable vehicle to issue and serve thecitations. This is an example of “micro-processing” (discussed furtherbelow) which increases the efficiency of the mobile enforcement byreducing the number of times the mobile enforcement vehicle may berequired to stop while accomplishing “real-time” issuance of citations.

FIG. 3 illustrates an example embodiment of a PEO operating a mobileenforcement vehicle 310 to patrol various parking stalls. Detailsregarding the mobile enforcement vehicle have been described in issuedU.S. Pat. No. 7,355,527 (“Franklin”) and is incorporated by referenceherein. The vehicle in the present example embodiment is patrollingparallel parking stalls, travelling in a direction parallel to theorientation of the parked vehicles. It can be appreciated that themobile enforcement vehicle may be either specifically configured todetect and patrol vehicles parked in various other types of parkingstall configurations, including angled and rectangular parking stalls orgenerally configured to handle all configurations.

In some embodiments, the mobile enforcement vehicle may travel at aspeeds of typically 50-km/h along its patrol route, while scanningparking stalls and parked vehicles but may go faster or slower dependingon the circumstances. The mobile enforcement vehicle generally cannotsee around a parked vehicle to verify parking stall numbers in order todifferentiate one parking stall from another, unlike handheldenforcement which permits the PEO to easily ascertain the parking stallnumber and delineate one stall from another by moving around a parkedvehicle to identify various visual clues associated with the parkingstall and the parked vehicle. Accordingly, one of the challenges thatmay be faced by the mobile enforcement vehicle in pay-by-space parkingis with respect to differentiating one parking stall from another andidentifying the corresponding parking stall number.

To improve the scanning accuracy of the mobile enforcement vehicle,parking stall signs indicating the parking stall number may be providedproximally to the parking stalls so as to permit the patrol vehicle'svision system to read them. The parking stall signs may be designed tominimize image sensor blooming effects to enhance visibility. Forexample white lettering on a black background may be used to improveimage contrast to compensate for blooming effects. Using flat black andnon-reflective backgrounds upon which light coloured letters and numbersare printed tends to enhance visibility, clarity and legibility ofparking stall signs. The text colouring for printing on a darkbackground may include white or yellow to provide optimal legibility. Inother instances, specific font faces may be preferable to make machinereadable signs. For example, spatial fonts can be used such thatexpansion due to detector blooming does not crowd into the adjacentletters. Choosing a larger font size for the sign can also improvevisibility, clarity and legibility. Other physical attributes of thesigns may also help improve machine readability. For example theaddition of hooding or other methods to prevent excess light fromcausing image overexposure may help reduce sensor blooming. In someother examples, the surfaces of the signs may be coated with a materialsuch as silicone to shed water, dirt, snow, ice, and other debris toenhance visibility. The various techniques described herein are notintended to be exhaustive and are intended as examples that can be usedalone or in combination to improve the visibility, clarity andlegibility of parking stall signs.

The captured image of the stall sign can then be processed using opticalcharacter recognition (OCR) to identify the stall number. In some cases,the captured images may be additionally or alternatively be reviewed andrecognized by a reviewing PEO or clerk.

In some cases, the camera used to capture the parking stall sign mayalso be used to capture other scene information, such as, for example,background and foreground information around the parking stall sign.This may further assist with identifying the parking stalls uniquely bycapturing and processing additional information, such as surroundingparking stall identification, road surface markers representing stalldemarcation (such as white paint on the ground), etc. In someembodiments, the camera used to capture foreground, background and theparking stall sign should preferably be capable of generating an imagewhose image resolution corresponds to a minimum of a megapixel level,such as, for example, a resolution of 4 megapixels.

The vision system of the mobile enforcement vehicle may also comprise anumber of cameras to obtain vehicle-identifying information includingthe license plate number, colour, the make and model, the vehicle'sprofile, etc. In some embodiments, a contactless speed measurementdevice, such as a Doppler microwave speedometer, may be used todetermine the precise speed of the mobile enforcement vehicle so as toallow precise triggering of the positioning and vision system to capturean image of a parked vehicle within the field of view of the camera andprovide very precise GPS coordinates. In other embodiments, a dedicatedlicense plate camera may be used as a part of a license plate reader(LPR) system. This dedicated camera may also be used to captureadditional information including stall demarcation to provideredundancy.

In yet other embodiments, machine-readable wireless transponders orradio-frequency identification (“RFID”) tags encoded with the parkingstall number may be used as stall signs instead of OCR-compatible signs.In this implementation, the mobile enforcement vehicle may be equippedwith a narrow-beam reader to read the transponder or RFID tags toidentify the parking stall number. It would be appreciated that thenarrow-beam reader is highly directional so that the mobile enforcementvehicle would be able to read the transponder or tag only when the beamis aimed at the tag from a certain direction. A narrow-beam reader mayhelp avoid “false readings” of nearby sparking stall tags and therebyincrease the likelihood of correctly identifying the stall number of theparking stall being patrolled. Since the mobile enforcement vehicle mayrely on a positioning system such as an onboard GPS to determine whichparking stall it is proximal to, implementation of transponder or RFIDstall tags may be useful in situations where a GPS signal is generallynot available, such as in underground parking lots or indoor parkingstalls. In environments where the GPS signal is available, the use oftransponders or RFID tags may allow relaxation of the precision requiredof the positioning system.

Another challenge that may be faced by the mobile enforcement vehicle isthe task of associating a parked vehicle to a parking stall. In otherwords, given the proximity of parking stalls and parked vehicles, themobile enforcement vehicle may be required to “place” a parked vehicleinto the correct parking stall. The method used to determine whether avehicle is stationary or in motion has been previously described inissued U.S. Pat. No. 7,355,527 (“Franklin”) and is incorporated byreference herein. Having entered a parking zone defined as Pay-by-Spaceand detecting a parked vehicle, the mobile enforcement vehicle 310 mayproceed to determine which parking stall the vehicle is occupying. To doso, the position (e.g. GPS coordinates) of the parked vehicle shouldpreferably be determined as precisely as possible so that the parkedvehicle can be “placed” into the boundaries of the parking stall asdefined by the four corners of the stall. In some embodiments, therelative positioning between the parked vehicle and the mobileenforcement vehicle 310 may be used to determine the position the parkedvehicle. Since the GPS coordinates of each parking stall may be recordedprior to its use, the mobile enforcement vehicle 310 may therefore useits own GPS coordinates to determine the GPS coordinates of the parkedvehicle and associate that parked vehicle to a given parking stall.

FIG. 4 illustrates one embodiment in which the position of a parkedvehicle may be determined based on relative positioning. The mobileenforcement vehicle 310 may be equipped with a GPS system 410 used todetermine the position the mobile enforcement vehicle 310 as it patrolsthe various parking stalls. An accurate GPS system may be desirable todetermine the GPS position the mobile enforcement vehicle 310, fromwhich the GPS coordinates of the parked vehicle 430 can be ascertained.

In some embodiments, where real-time determination of parking violationsis not necessary, inertia equipped GPS may be used to obtainhigh-accuracy positioning data (generally to within 2.5 meters) usingpost-processing techniques. In such instances, post-processing refers tothe collection of GPS and associated data during a patrol and processingthe collected data at a later time after the patrol to enhance theaccuracy of the positioning data. Such a technique may yield highaccuracy results even in challenging environments such as urbanlocations where GPS signal interference as a result of multi-path signalpropagation is commonplace. Post-processing of the vehicle GPS datausing secondary GPS information obtained from a fixed-location GPSsource may be used to apply environmental corrections to reduceuncertainty of the measured GPS locations.

In one example, while on patrol, satellite information from multiplenavigation or positioning sources such as the Global Positioning System(GPS), the Global Navigation Satellite System (GLONASS) and the Galileonavigation satellite system etc. is logged in real-time by the mobileenforcement vehicle. The data collected include but is not limited tolatitude, longitude, altitude, satellite geometry, estimated errors,number of satellites in communication with the mobile enforcementvehicle and date/time. Simultaneously, the mobile enforcement vehiclecan also collect detailed logs of outputs from onboard gyroscopes,accelerometers, digital compasses or any other measurement device thatcan later be used to improve the GPS positioning in challengingenvironments. At the moment that a parked vehicle is detected by themobile enforcement vehicle, the GPS time corresponding to this event islogged and saved along with other data such as, but not limited tolatitude, longitude, bearing, and orientation of the mobile enforcementvehicle, and the dimensions and photographs of the parked vehicle. Next,all of the logged information is synchronized to a database server orany suitable data storage device for post processing. Any inaccuraciesof the real-time GPS data is then corrected by blending in the variouscomplementary device data as well as the secondary GPS base station databy going backwards and forwards in time until the data converges to asolution. The mobile enforcement vehicle GPS time stamps associated withthe detection of the parked vehicle (“detection event”) is thencross-referenced against the corrected GPS data. For example, two datapoints from the corrected data set whose associated time stampscorrespond to a time just before and just after the detection event canbe used to estimate the position of the parked vehicle at the precisetime of the detection event through data interpolation. This is requiredbecause the sampling rates of the corrected GPS data may vary and willoften never exactly match the GPS time stamps of the real-time GPS dataunless an infinite sampling rate was used.

It can be appreciated that to correctly associate a parked vehiclewithin a parking stall, precise determination of the GPS coordinates ofthat vehicle is necessary. A variance or uncertainty of, for example, 5meters is unacceptable since this value can be large enough to offsetthe parked vehicle into neighboring parking stalls.

In the various embodiments disclosed herein, the GPS coordinates of themobile enforcement vehicle are used to determine the GPS coordinates ofthe parked vehicle. In the present embodiment, the mobile enforcementvehicle 310 may further be equipped with a laser triggering system 420configured to detect a parked vehicle with precision, determine theproximity between the parked vehicle and patrol vehicle, and to measurethe dimensions of the parked vehicle. For example in some embodiments,the laser triggering system 420 is oriented perpendicular to thelongitudinal axis corresponding to the length of the mobile enforcementvehicle. In some other embodiments, the laser triggering system 420, isangled (i.e. sloped) downwards at 25 degrees relative to a horizontalreference plane while emitting a beam that is 90 degrees to thedirection of the mobile enforcement vehicle. It should be noted that themounting angles of the laser described here are merely examples ofpossible mounting configurations. In the various embodiments disclosedherein, the angle of the laser triggering system in the lateraldirection or vertical direction (i.e. the angle of slope) generallydepends on the mounting position of the laser triggering system on themobile enforcement vehicle 310 as well as characteristics of mobileenforcement vehicle 310 (e.g. size, height etc.) upon which the lasertriggering system is mounted.

As the mobile enforcement vehicle 310 passes the parked vehicle 430, thelaser may trigger as it detects the corner at one end 440 of the parkedvehicle 430 and scans across the parked vehicle to the corner at theother end 445 at a given sampling or scanning frequency. If the vehicleis parked in parallel to the direction of travel of the patrol vehicleas illustrated in FIG. 4, the laser may scan along the length of theparked vehicle 430 to determine its length. If the vehicle is parkedperpendicular to the direction of travel, then the parked vehicle'swidth may be scanned to determine the width of the parked vehicle 430.This method of scanning may allow the mobile enforcement vehicle todetermine the length or width (whichever the case may be) accurate toapproximately 8 centimeters. Combined with the detected speed of themobile enforcement vehicle and collected GPS data, the positioning ofthe first 440 and second end 445 of the parked vehicle may bedetermined.

Furthermore, the laser 420 may also indicate the distance between patrolvehicle and the parked vehicle. Based on this information as well as theprecise GPS position of the patrol vehicle, the GPS coordinates of thecenter of the parked vehicle 430 may be calculated using, for example,the Vincenty Direct formula. For example, as illustrated in FIG. 4, ifthe vehicle is parked parallel to the direction of travel of the mobileenforcement vehicle, then the center of the parked vehicle 450 can bedetermined by 1) adjusting the GPS position of the patrol vehicle at thecompletion of the laser scan by offsetting (i.e. moving back) thatposition by an amount equivalent to half the length of the parkedvehicle in the axis corresponding to the vehicle's length and 2)offsetting (i.e. moving over) the GPS position of the mobile enforcementvehicle at the completion of the scan by half a standard width of avehicle (standard widths may be used since the actual width is unknown)plus the lateral distance between the parked vehicle and the mobileenforcement vehicle in the axis corresponding to the parked vehicle'swidth.

The parked vehicle 430 may then be associated to a given parking stallby comparing the GPS coordinates of the stall and the parked vehicle430. In one embodiment, the GPS coordinates corresponding to the fourcorners of the parking stall may be used to set the boundaries and thegeometric center of the stall, and the geometric center of the stall maybe compared to the GPS coordinates of the parked vehicle to associatethe parked vehicle 430 to a given parking stall.

In another embodiment, the accuracy of the process of associating aparked vehicle to a given parking stall may be enhanced using alaterally extended polygon based on the direction of travel of themobile enforcement vehicle 310. The polygon may be defined toencapsulate the geometric center of the parking stall to better reducelateral GPS errors. Therefore if the center of the parked vehicle 430 iscontained within the extended stall polygon, then it may be concludedthat the parked vehicle is occupying the stall. The polygons used inthis embodiment may be of any shape, including triangles, rectangles,and squares etc. In some cases, in order to maintain accuracy to withina 2.5 meter radius, a square polygon is preferred when dealing with arectangular parking stall.

The information collected while parked vehicles are scanned by themobile enforcement may be processed in real-time or in batches in a postprocessing procedure. If post processing is performed, GPS data enhancedwith data provided by the mobile enforcement vehicle's inertial guidancesystem (e.g. gyroscopic plus speed measurements, as describedpreviously), may be combined to obtain positioning accuracy to less than2.5 meters, even under environmental conditions where GPS signalreception is not ideal.

Enforcement of Pay-by-Space Parking

In some embodiments, the central processor along with the database maybe used to manage and track the usage of each parking stall for a givenparking lot or parking area. FIG. 5 illustrates an example of thevarious fields of the database 500. The database may be used by thecentral processor to store and retrieve parking enforcement rulesimposed on a given parking stall within the parking lot to facilitateidentification of parking violations.

In some embodiments, the database may comprise a “Parking stall No.”field 510 which stores the unique parking stall numbers corresponding toeach parking stall being managed. The “Stall Type” field 520 may be usedto specify the type of parking stall. For instance, type CA′, ‘P’ and CRmay refer to angled, parallel and rectangular stalls, respectively. The“Stall Coordinates” field 530 may be used to indicate the GPScoordinates of each corner of the parking stall. Using informationconcerning the type of stall indicated in the “Stall Type” field 520 and“Stall Coordinates” field 530, the boundaries of any given parking stallmay be ascertained by the central processor or the mobile enforcementvehicle associate a parked vehicle to a parking stall.

The “Occupied?” field 540 may be used to specify whether a given parkingstall should be occupied (i.e. it may be occupied if it has been paidfor). If a parking stall has been paid for, the “Payment Time” field 550and the “Expiry Time” field 560 may be populated with the time paymentwas made (i.e. indicating the parking start time) and the time theparker should vacate the stall (i.e. parking end time), respectively.Finally, the “Stall Data” field 570 may be used to storevehicle-identifying information obtained from the vision system of themobile enforcement vehicle 310 such as the license plate number, colour,vehicle profile etc. The “Stall Data” field 570 may store one or moredatasets to form a dataset group 575, wherein each dataset may containvehicle-identifying information observed at a given parking stall duringa patrol. For instance, dataset 571 may correspond to data recorded fromthe most recent patrol and data set 572 may correspond to theimmediately preceding patrol. In some embodiments, each data set may betime-stamped to specify the time at which the data was acquired so as topermit the central processor to track the use of the parking stall.Therefore, the dataset group may provide useful stall-specific usageinformation for the parking authority. This information may be used todetermine optimal patrol schedules and patrol routes.

Referring now to FIGS. 6A and 6B, shown therein is a process flowdiagram illustrating method 600 for a basic pay-by-space parkingenforcement. The method 600 begins at step 610 such that, prior toparking stall use, the GPS coordinates of each parking stall in theparking area may be determined and stored into the database. During useof the parking area, at step 620, a parking request may be received bythe central processor from a parker indicating the stall numbercorresponding to the stall used by the parker and the desired parkingduration. The parking request may be generated by a parking kiosk,parking meter, an application operating on the parker's smartphone orany other appropriate generation method. In some embodiments the parkingrequest may also include payment information for the central processor.In other embodiments, the parking kiosk or parking meter may handlepayment separately.

At step 630, the information received from the parker may be recorded inthe database. For example the time of the parking request may berecorded in the “Payment Time” field 550 of FIG. 5, and the status ofthe parking stall may be updated by the central processor to indicate“occupied” in the “Occupied?” field 540. The corresponding expirationtime may be calculated using the time of payment and the desired parkingduration indicated by the parker.

While on patrol, the mobile enforcement vehicle may scan the parkingstalls to determine the stall numbers and transmit this informationalong with the time of scan (i.e. time of observation) to the centralprocessor. In some embodiments, the mobile enforcement vehicle may scanboth empty and occupied stalls. The mobile enforcement vehicle mayindicate to central processor whether or not the transmitted stallnumber corresponds to an empty or an occupied stall using an appropriateindicator. In some embodiments, the mobile enforcement vehicle maytransmit parking stall information as they are scanned, in real-time. Inother embodiments, the scans may be made first and transmitted later inbatches. At step 640, the central processor may receive and store theparking stall numbers of occupied parking stalls and the time ofobservation. Next, at step 650, the central processor may proceed toanalyze the received information for the identified stall if it isoccupied to determine whether there is a parking violation.

FIG. 6B depicts a process flow diagram showing further details of step650 of FIG. 6A in which a parking violation may be detected at a givenparking stall. At decision step 654, the central processor may query thedatabase to determine whether or not, at the time of observation, theparking time for the identified parking stall has expired. Thisdetermination may be made using the parking expiration time stored inthe “Expiry Time” field 560 of FIG. 5 and the time of observationreceived in step 640. In other words, the central processor checks todetermine whether the parking stall in question has been paid for at thetime of observation.

If the time of observation is a later time than the time of expiration,then the parking stall should not be occupied (i.e. answering “No” atdecision step 654), since the parking time has expired. In this case,the method proceeds to step 670 to trigger an infraction alert. In someembodiments an infraction alert may be indicated by setting a violationstatus indicator associated with the parking stall to indicate aviolation. The status indicator may subsequently be transmitted to themobile enforcement vehicle at step 672 so that a citation may be issued.In the alternative, if the parking stall has been paid for, noinfraction has occurred, status indicator is set to indicate that noviolation has occurred and the method proceeds to step 675 in which themethod 600 may end. The central processor may notify the mobileenforcement vehicle via the status indicator that there is no infractionand the mobile enforcement vehicle may move on to the next occupiedparking stall.

The procedure illustrated by method 600 allows the parking authority todetermine a window of time or parking period during which a parker isallowed to park. This window of time may be defined using a time of daycorresponding to the start of the parking period (e.g. the time of theparking request made) and a time of day corresponding to the end of theparking period (e.g. the expiration time where vehicles are not allowedto occupy the stall). In the illustrated embodiments of FIGS. 6A and 6B,a vehicle may use this parking stall within the window, while use of thesame parking stall outside of this window would result in issuance of acitation. For example, if a parker makes a parking request for a givenparking stall at 10 am for two hours, then the central process maydetermine that the parking window or parking period runs from 10 am to12 pm, where 12 pm is the parking expiration time. Accordingly, avehicle parked in the parking stall within this window will be allowedto park without any violations or citations.

In the illustrated embodiments of FIGS. 6A and 6B, it is assumed that aslong as the parking stall is paid for, any vehicle can park in thatstall within the allowed window without resulting in any violations orissuance of citations. Such a policy may be governed by the laws and/orpractices of each jurisdiction, and may differ from one jurisdiction toanother. For example, using the example above, in one jurisdiction, ifthe parker who paid for parking at 10 am for two hours vacates theparking stall at 11 am, a subsequent parker may occupy that stall, forfree and without any violation, from 11 am to 12 pm. However, in someother jurisdictions, as discussed below, the practice and/or the law mayrequire every new parker to pay for whatever time they use, even if itcompletely overlaps the previously paid time. In other words, even if aparking stall is paid for from 10 am to 12 pm, a new parker parking inthe parking stall at 11 am will be required to pay for the entire timethat parker decides to park in the parking stall, even if it results indouble billing from 11 am to 12 pm. This discussed in more detail belowwith reference to, for example, FIGS. 7A and 7B.

Referring back to FIGS. 6A and 6B, it would be appreciated that thepreceding description of pay-by-space enforcement may be subject todetection of infractions where an infraction should not be issued. Forexample, it would not be fair to the parker if, shortly after parkingthe vehicle but before the parker reaches the parking kiosk to pay, amobile enforcement vehicle patrols the recently parked vehicle andissues a citation (i.e. parking outside the window). Therefore, it maybe preferable for the parking authority to provide a grace period toallow the parker to park his or her vehicle and to then proceed to payfor parking at a parking kiosk located some distance away from thechosen parking stall. In the various embodiments disclosed herein,automated post processing methods may be applied to reduce theincidences of incorrectly identifying a parking infraction. Forinstance, post-processing may be used to introduce parking grace-periods(e.g. 10 minutes) before and after the parking session ends. If, forexample, parking citations are processed and consolidated in apost-processing procedure at the end of the day, then the centralprocessor would have detected that shortly after issuing a citation forthe parking stall (for example, within 2 minutes), a parking request wasmade for that stall. If a grace period policy was in place, then thecentral processor may be configured to waive the citation since it waslikely issued in error. This post-processing step may also be applied toaccommodate a parker wishing to extend his/her parking time by addingmore funds to a just-expired parking stall.

In the various embodiments disclosed herein, other methods of automatedpost processing may also be applied to reduce the incidences ofincorrect parking infractions. For example, GPS positioning correctionssuch as those described above may be applied to enhance identificationof the correct parking stall, which may be particularly useful when themobile enforcement vehicle is operating in dense urban areas wheresatellite navigation signals are prone to multi-path distortions.Identification of the correct parking stall may be further enhancedusing reference photo(s) background (e.g. those that are images of theparking stall only, without the presence of a parked vehicle) andcompared to those acquired by the mobile enforcement vehicle during itspatrols. Optionally, the enhanced data can be further reviewed manuallyby a PEO to efficiently step forward or backward between images of theparking stall being examined with neighbouring stalls and betweenreferences images and images acquired during the patrols.

Under the basic enforcement method of FIGS. 6A and 6B, as discussedabove, if a parker leaves a parking stall with remaining parking time, asubsequent parker may park at the stall without payment for at least theduration of time equal to the remaining time without triggering aninfraction alert. In other words, as long as a parking stall is paidfor, no parking violation is detected irrespective of who paid for theparking.

In some instances, the parking authority may desire that all new parkersmust pay for parking even if the stall used by the new parker has unusedtime remaining. For example, some jurisdictions have a policy thatspecifies that the new parker must pay for whatever time they use, evenif it completely or partially overlaps with the previously paid time.One method of enforcing such a policy may be to avoid indication of thetime remaining for a parking stall so that subsequent parkers would beunaware of whether the parking stall may be used for free. However, aprevious parker can nonetheless inform a subsequent parker that a givenstall has unused time. Alternatively, a previous parker can pass his orher parking voucher, obtained at the time payment for parking was made,to a subsequent parker so that the latter party can continue to use agiven stall for free.

The issue of voucher pass-backs may be addressed with the assistance ofthe mobile enforcement vehicle. It may be understood that the mobileenforcement vehicle may patrol a parking area on a regular basis toidentify parking violations. Therefore, the mobile enforcement vehiclemay be used to determine whether a parker is “invalidly” using apaid-for parking stall. In this instance, an “invalid” use constitutes asubsequent parker using a previous parker's remaining unused parkingtime for a given parking stall.

FIGS. 7A and 7B show a process flow diagram illustrating method 700 ofpay-by-space parking enforcement for detection invalidly parkedvehicles. Steps 710-730 of method 700 correspond to steps 610-630 ofmethod 600 described previously. While on patrol, the mobile enforcementvehicle may scan the parking stalls to determine the stall numbers andtransmit this information along with the time of scan (i.e. time ofobservation) to the central processor. In some embodiments, the mobileenforcement vehicle may scan both empty and occupied stalls. The mobileenforcement vehicle may indicate to central processor whether or not thetransmitted stall number corresponds to an empty or an occupied stallusing an appropriate indicator. In some embodiments, the mobileenforcement vehicle may transmit parking stall information as they arescanned, in real-time. In other embodiments, the scans may be made firstand transmitted later in batches.

During the patrol of the parking stalls, the mobile enforcement vehiclemay also scan and transmit vehicle-identifying information of thevehicle occupying a given stall, the stall number and the time ofobservation to the central processor. The information may include one ormore identifies, such as the license plate number, make and model andthe colour of the vehicle. At step 740, the central processor mayreceive the parking stall numbers, vehicle-identifying information andthe time of observation. The central processor may proceed to associatethe vehicle-identifying information to the identified parking stall,along with any previously received information (e.g. those obtained attime of payment by the parker or an earlier patrol). In someembodiments, if the parking vouchers are RFID enabled, the mobileenforcement vehicle may be equipped with an RFID reader to read andtransmit to the central processor the parking voucher identification(“ID”) number. At step 750, the central processor may analyze thereceived information corresponding to the identified stall if it isoccupied to determine whether there is a parking violation.

FIG. 7B depicts a process flow diagram showing further details of step750 of FIG. 7A in which a parking violation may be detected at a givenparking stall. At decision step 754, the central processor may query thedatabase to determine whether or not, at the time of observation, thepermitted parking time at the identified parking stall has expired in amanner similar to step 654 of FIG. 6B. If the parking stall should notbe occupied (i.e. answering “No” at decision step 754 because theparking time has expired) the method may proceed to steps 770 and 772 toissue a citation in a manner similar to steps 670 and 672 of method 600described in FIG. 6B. If the parking stall is paid for (i.e. answering“Yes” at decision step 754), the method may proceed to decision step 756where a comparison of the vehicle-identifying information obtained forthe given parking stall during the most recent patrol and theimmediately preceding patrol is made. If no difference is observed inthe comparison, then it may be concluded that the same vehicle has beenoccupying the paid-for parking stall during the two patrols and thevehicle is validly parked (i.e. answering “No” at step 756) so themethod may proceed to step 775 in which the method may end.

In the alternative, if the comparison of vehicle-identifying informationat step 756 indicates that there is a difference (i.e. answering “Yes”at decision step 756), the difference may suggest that a new parker hasoccupied the parking stall at some time between the two patrols, and themethod proceeds to decision step 758. At decision step 758, the centralprocessor may determine whether a parking request and payment for thestall in question has been made by the new parker. In the presentembodiment, the central processor may query the database to determinewhether a parking request and payment for the parking stall in questionwas made between the two patrols. Where a parking request and paymenthas been made (i.e. answering “Yes” at step 758), then it may beconcluded that the vehicle parking in the stall is a new vehicle whichhas paid for parking, and is thus validly parked. The method may proceedto step 775 and the method ends. Otherwise, it may be concluded that theparked vehicle is using a previous parker's unused parking time and thata citation should be issued (i.e. answering “No” at step 758) and themethod proceeds to step 770 to trigger an infraction alert. As describedin method 600, the violation status indicator for the parking stall maybe set to indicate a violation and transmitted to the mobile enforcementvehicle. In turn, the mobile enforcement vehicle may make note of thestatus and issue a citation.

FIGS. 8A and 8B show a process flow diagram illustrating method 800 ofpay-by-space parking enforcement which makes use of the parked vehicle'slicense plate number as vehicle-identifying information.

Steps 810-830 of method 800 are similar to steps 610-630 of method 600described previously. However, in this method, the parker may be askedto provide the parked vehicle's license plate number asvehicle-identifying information at the time of payment. By providingsecondary, vehicle-specific information such as the license platenumber, the process of detecting parking violations for both the centralprocessor and the mobile enforcement vehicle may be simplified. From themobile enforcement vehicle's perspective, determining only the licenseplate number and the stall number may speed up the patrol process byreducing the amount of information that must be recorded. For thecentral processor, a parking violation (i.e. “invalid” parking) can bedetermined by simply comparing the license plate number identified bythe parking enforcement vehicle and the license plate number obtainedfrom the parker at the time of payment. In some cases, a difference inphysical vehicle characteristics (e.g. size, shape or colour) may beobserved which triggers a caution to indicate that additional scrutinyof the parked vehicle is required. For example, a PEO may be dispatchedto obtain or verify the license plate number, the associated vehicleidentification number (VIN) or both. The VIN number and the licenseplate number may be verified by cross-referencing the observedinformation with official vehicle registration information provided by athird-party database.

Asking the parker for secondary information such as the license platenumber may allow for more advanced types of enforcement. For example, aparticular parking authority may offer subscription-based pay-by-spaceparking in which a parking subscriber may be allocated a specificlong-term parking stall. Long-term parking in this instance may includeparking subscriptions which permit a parker to park at a given parkingstall for more than one day. Parking subscriptions may be given atparking lots serving office buildings, hotels, and airports. In someembodiments of long-term pay-by-space parking, the parking authority mayassign the parker a parking stall to a license plate. In otherembodiments, the parking authority may permit the parker to specifymultiple license plates so as to allow a parker owning multiple vehiclesto use the same stall. Regardless of the parking arrangement madebetween the parker and the parking authority, subscription pay-by-spaceparking and on-demand pay-by-space parking may be enforced through theapplication of method 800 described further in detail below.

While on patrol, the mobile enforcement vehicle may scan the parkingstalls to determine the stall numbers and transmit this informationalong with the time of scan (i.e. time of observation) to the centralprocessor. In some embodiments, the mobile enforcement vehicle may scanboth empty and occupied stalls. The mobile enforcement vehicle mayindicate to central processor whether or not the transmitted stallnumber corresponds to an empty or an occupied stall using an appropriateindicator. In some embodiments, the mobile enforcement vehicle maytransmit parking stall information as they are scanned, in real-time. Inother embodiments, the scans may be made first and transmitted later inbatches. During patrol of the parking stalls, the mobile enforcementvehicle may also record and transmit the license plate number of thevehicle occupying a given stall, the stall number and the time ofobservation to the central processor.

At step 840, the central processor may receive the parking stall numberand license plate number, both of which may be contained in one or morephotos acquired by the vision system, and the time of observation. Whenthe information is received, the processor may associate thevehicle-identifying information with the parking stall, along with anypreviously received information (e.g. at time of payment by the parkeror previous patrol) for the parking stall. At step 850, the centralprocessor may analyze the received information corresponding to theidentified stall to determine whether there is a parking violation.

FIG. 8B depicts a process flow diagram showing further details of step850 of FIG. 8A in which a parking violation may be detected at a givenparking stall. At decision step 854, the central processor queries thedatabase to determine whether or not, at the time of observation, thepermitted parking time at the identified parking stall has expiredsimilar to step 654 of FIG. 6B. If the parking stall should not beoccupied (i.e. answering “No” decision step 854 because the parking timehas expired) the method proceeds to step 870 and 872 in a manner similarto steps 670 and 672 of method 600 described in FIG. 6B in which acitation should be issued for occupying an unpaid or expired parkingstall.

If the parking stall is paid for (i.e. answering “Yes” at decision step854), the method may proceed to decision step 856, where the licenseplate number obtained for the given parking stall from the most recentpatrol and the license plate number obtained at the time of payment maybe compared. If the comparison shows that the license numbers are thesame, then it may be concluded that the same vehicle has been occupyingthe paid-for parking stall since the time of payment to the time of thepatrol and the vehicle is validly parked (i.e. answering “Yes” atdecision step 756). Therefore, the method may proceed to step 775 inwhich the method may end.

In the alternative, if the comparison of the license plate numbers atdecision step 756 indicates that there a difference (i.e. answering “No”at decision step 756), the difference may suggest that a new parkerbegan occupying the parking stall sometime between the time of paymentand the time of the patrol. The difference may also suggest that the newparker may be using the previous parker's unused time. Accordingly, themethod may proceed to step 870 and 872 to trigger an infraction alertand issue a citation, respectively. Similar to method 600, the violationstatus indicator for the parking stall may be set to indicate aviolation and transmitted to the mobile enforcement vehicle. In turn,the mobile enforcement vehicle may make note of the status and issue acitation. In some instances citations may be issued after a review bythe PEO or a clerk to verify the infraction. In other instances,citations are issued in real time and placed (served) on the windshieldof the parked vehicle. Where citations are processed in batches (i.e.post-processed citations) after completion of a patrol, those citationsare mailed to the owner of the vehicle.

Referring now to FIGS. 9A and 9B shown therein is a process flow diagramillustrating method 900 of pay-by-space parking enforcement in which theparker does not provide any information to the central processor otherthan paying for a parking location (i.e. no parking stall informationand no secondary vehicle information such as license plate informationis provided by the parker at the time of payment). Steps 910-920 ofmethod 900 generally correspond to steps 610-620 of method 600 describedpreviously. However, step 920 further provides that a machine readableparking voucher with a uniquely assigned identification (“ID”) numbermay be issued to the parker. The parker may be required to place thevoucher on the front dashboard for display through the windshield or inany location of the parked vehicle that would allow scanning of thevoucher by the mobile enforcement vehicle. In some embodiments theunique identification number may be encoded within an RFID tag so thatthe mobile enforcement vehicle equipped with an RFID reader may read theencoded voucher ID number as the vehicle moves along its patrol route.In other embodiments, an optically scannable image corresponding to theID number, such as a barcode or QR code, may be used to encode thevoucher ID number, which may require the parker to place the parkingvoucher in a location of the vehicle so that the voucher may bescannable by the mobile enforcement vehicle's vision system.

At step 930, upon issuance of the voucher, the relevant informationpertaining to the parking request, including the time of issuance andparking expiration time may be associated by the central processor tothe parking voucher ID number and recorded in the database. At thispoint the central processor may not have knowledge of which issuedvoucher is being used with which parking stall.

While on patrol, the mobile enforcement vehicle may scan the parkingstalls to determine the stall numbers and transmit this informationalong with the time of scan (i.e. time of observation) to the centralprocessor. In some embodiments, the mobile enforcement vehicle may scanboth empty and occupied stalls. The mobile enforcement vehicle mayindicate to central processor whether or not the transmitted stallnumber corresponds to an empty or an occupied stall using an appropriateindicator. In some embodiments, the mobile enforcement vehicle maytransmit parking stall information as they are scanned, in real-time. Inother embodiments, the scans may be made first and transmitted later inbatches and subsequently analyzed in the parking office.

During the patrol, the mobile enforcement vehicle may also record andtransmit to the central processor vehicle-identifying information (e.g.color, make and model, and license plate number) corresponding to thevehicle occupying a given stall, the stall number, the time ofobservation and the ID number of the voucher. In some instances, themobile enforcement vehicle may not be able to scan the identificationnumber during its patrol. In that case, a notification to a PEO may besent to direct the PEO to the parking stall in question so that a manualscan may be performed. If the manual scan successfully identifies thevoucher ID number, then the voucher ID number along with the parkingstall number and vehicle-identifying information may be transmitted tothe central processor. Otherwise, the failed manual scan may indicatethat the parker did not purchase a parking voucher, which may justifyissuance of a citation.

At step 940, the central processor may receive the stall number,vehicle-identifying information, and voucher identification number for agiven stall. An association or a link between the voucher ID number andparking stall number may be established if the identified voucher IDnumber has not been previously associated with a parking stall. In someembodiments, association of a new voucher ID number to a stall mayterminate the parking voucher previously associated with that parkingstall. As a result, the previous voucher may not be used further.Therefore, detection of a terminated voucher ID number may trigger aninfraction alert if the voucher ID number was detected in associationwith a parked vehicle. At step 950 the central processor analyzes thereceived information corresponding to the identified stall to determinewhether there is a parking violation.

FIG. 9B depicts a process flow diagram showing further details of step950 of FIG. 9A in which a parking violation may be detected at a givenparking stall. At decision step 954, the central processor may determinewhether or not, at the time of observation, the permitted parking timeat the identified parking stall has expired. To do so, the centralprocessor may query the database using the parking voucheridentification number to obtain the expiration time assigned to theparking voucher. If the parking time has expired, then the parking stallshould not be occupied (i.e. answering “No” at decision step 954) andthe method proceeds to steps 970 and 972, in a manner similar to themethod described in FIG. 6B, in which a citation should be issued foroccupying an unpaid or expired parking stall. If the parking stall ispaid for (i.e. answering “Yes” at decision step 954), the centralprocessor may proceed to decision step 956 to determine, for the givenstall, whether the voucher ID number identified from the most recentpatrol is different from the voucher ID number identified from theimmediately preceding patrol. If there is a difference (i.e. answering“Yes” at decision step 956), then it may be concluded that a new parkerhas paid for parking and the vehicle currently occupying the stall isvalidly parked so that the method may proceed to step 975 and end.

On the other hand, if the voucher ID number assessed at step 956 is thesame, then the method may proceed to step 958 to perform a comparison ofthe vehicle-identifying information obtained during the most recentpatrol and the immediately preceding patrol. If the comparison revealsthat the vehicle-identifying information is the same (i.e. answering“No” at decision step 958), then it may be concluded that the vehicleoccupying the parking stall has not changed during the two patrols andthe vehicle is validly parked so that the method may proceed to step 975and end. If the comparison reveals that the vehicle-identifyinginformation is different (i.e. answering “Yes” at decision step 958),then it may be concluded that a new parker has occupied the parkingstall using a previously purchased parking voucher. In other words, avoucher pass-back event may be detected. The method may then proceed to970 and 972 in a manner similar to the method described in FIG. 6B inwhich a citation should be issued for occupying an unpaid or expiredparking stall.

Issuance of Citations

As discussed previously, the mobile enforcement vehicle may scan andcollect parking stall information at a much higher speed than manualparking enforcement. The level of efficiency, however, may besignificantly reduced if the patrol vehicle must stop each time itencounters a parking violation to issue a citation. In some embodiments,the technique of micro-processing may be used to issue citations in amore efficient manner. The stall numbers corresponding to occupiedparking stalls for which citations are to be issued may be transmittedto another PEO who may then go directly to the citable vehicle to issueand serve the citations. The PEO receiving the transmission may be a PEOwho patrols on foot. Once the citation has been issued, the centralprocessor may be notified by the PEO which may in turn notify the mobileenforcement vehicle that generated the citation alert that the citedvehicle(s) have been processed.

For some cases, the GPS system may use micro-segments. Generally the GPSsystem must start and travel from a good GPS location and finish at agood GPS location. A good location is defined as to where the GPS hasexcellent satellite reception. Generally, in post processingmethodology, the GPS data is analyzed at the end of the day (or nextday), corrections applied using the INS (inertial navigation system)data, infractions determined and citations mailed. It is also possibleto analyze data every few minutes and send citations to follow up PEOsthat would track down and serve the citations on the windows of theinfracting vehicles.

To ensure an error-free assignment of citations, there may be a need tohave a human officer to review all potential citations and in particularoversee “ambiguous cases” (i.e. cases where it is unclear as to whethera citation is required) to confirm that issuance of a citation isneeded. In some situations, whether a parking violation has occurred maybe unclear. For instance, as a result of uncertainties with respect todetermining the position of a parked vehicle, it may be difficult to“place” the vehicle to a parking stall. A human officer may be needed tomanually examine images acquired during the patrol for the parking stallto make an assessment

It will be appreciated that numerous specific details are set forth inorder to provide a thorough understanding of the exemplary embodimentsdescribed herein. However, it will be understood by those of ordinaryskill in the art that the embodiments described herein may be practicedwithout these specific details. In other instances, well-known methods,procedures and components have not been described in detail so as not toobscure the embodiments described herein. The scope of the claims shouldnot be limited by the preferred embodiments and examples, but should begiven the broadest interpretation consistent with the description as awhole.

1. A method of managing a parking area, the parking lot comprising aplurality of parking stalls for occupancy by a plurality of vehicles,each parking stall being uniquely identifiable using a parking stallidentifier, the method comprising: receiving a parking authorizationrequest from a parking lot user, the parking authorization requestspecifying a parking stall identifier corresponding to a parking stallthat is occupied by a vehicle belonging to the parking lot user, theparking authorization request further specifying a parking durationparameter identifying a duration of time for which the parking lot usercan park the vehicle at the parking stall; determining a parkingduration rule for the parking stall based on the parking durationparameter, the parking duration rule indicating a parking expirationtime at which the vehicle must vacate; at a first time, receiving afirst data associated with the parking stall identifier, the first datacomprising an occupancy parameter indicating a presence or an absence ofa parked vehicle at the parking stall identified by the parking stallidentifier; if the occupancy parameter indicates a presence of a parkedvehicle, determining if the first time exceeds the parking expirationtime; and if the first time exceeds the parking expiration time,generating a citation alert for the parking stall identified by theparking stall identifier.
 2. The method of claim 1, further comprising:issuing a parking citation to the parked vehicle based on the citationalert.
 3. The method of claim 1, wherein the parking authorizationrequest further comprises a vehicle identifier identifying at least onecharacteristic of the vehicle, the method comprising: at the first time,further receiving a detected vehicle identifier corresponding to atleast one detected characteristic of the parked vehicle at the parkingstall, the at least one detected characteristic being comparable to theat least one characteristic; determining if the parked vehicle is thesame as the vehicle corresponding to the parking authorization requestby comparing the vehicle identifier and the detected vehicle identifier;if the parked vehicle and the vehicle corresponding to the parkingauthorization request are determined to be different vehicles,determining if a second parking authorization request is received fromthe parked vehicle; and if the second parking authorization request isdetermined to not have been received from the parked vehicle, generatingthe citation alert for the parking stall.
 4. The method of claim 3,wherein the at least one characteristic of the vehicle comprises a dataitem selected from the group consisting of a license plate number of thevehicle, year of make of the vehicle, model of the vehicle, color of thevehicle and transponder identity of the vehicle.
 5. The method of claim3, wherein the at least one detected characteristic of the parkedvehicle comprises a data item selected from the group consisting of alicense plate number of the vehicle, model of the vehicle, color of thevehicle, shape and length of the vehicle, and transponder identity ofthe vehicle.
 6. The method of claim 1, wherein the first time does notexceed the parking expiration time, wherein the first data furthercomprises a first detected vehicle identifier identifying at least onecharacteristic of the parked vehicle detected at the first time, andwherein the method further comprises: at a second time, where the secondtime does not exceed the parking expiration time, receiving a seconddata associated with the parking stall identifier, wherein the seconddata comprises a second detected vehicle identifier identifying at leastone characteristic of a parked vehicle detected at the parking stall atthe second time, wherein the second time is subsequent to the firsttime, and wherein the at least one characteristic of the parked vehicledetected at the first time and the at least one characteristic of theparked vehicle detected at the second time correspond to a same dataitem; comparing the first detected vehicle identifier to the seconddetected vehicle identifier; if the first detected vehicle identifierand the second detected vehicle identifier are determined to correspondto different vehicles, determining if a second parking authorizationrequest is received from the parked vehicle detected at the second time;and if the second parking authorization request is determined to nothave been received, generating the citation alert for the parking stall.7. A method of managing a parking lot using a patrol vehicle, theparking lot comprising a plurality of parking stalls for occupancy by aplurality of vehicles, each parking stall being uniquely identifiableusing a parking stall identifier, the method comprising: operating thepatrol vehicle to patrol the parking lot; determining, at a first time,for an occupied parking stall, a parking stall identifier; determining,at the first time, a parking duration rule for the parking stallidentifier based on a parking authorization request comprising a parkingduration parameter received from an operator of a vehicle occupying theoccupied parking stall, wherein the parking duration parameteridentifies a duration of time for which the vehicle can be parked at theparking stall, and wherein the parking duration rule indicates a parkingexpiration time at which the vehicle must vacate the parking stall; anddetermining if the first time exceeds the parking expiration time, andif so, generating a citation alert for the parking stall identified bythe parking stall identifier.
 8. The method of claim 7, furthercomprising: issuing a parking citation to a parked vehicle based on thecitation alert.
 9. The method of claim 7, wherein the first time doesnot exceed the parking expiration time, the method further comprising:determining, at the first time, a detected vehicle identifiercorresponding to at least one detected characteristic of a parkedvehicle at the parking stall; determining if the parked vehiclecorresponds to the vehicle associated with the parking authorizationrequest, wherein the parking authorization request further comprises avehicle identifier identifying at least one characteristic of thevehicle; if the parked vehicle does not correspond to the vehicleassociated with the parking authorization request, determining if asecond parking authorization request is received for the parking stallidentifier; and if the second parking authorization request isdetermined to not have been received for the parking stall identifier,generating the citation alert and issuing the parking citation to theparked vehicle.
 10. The method of claim 7, wherein the parking lot ispatrolled based on a prescheduled time.
 11. The method of claim 7,wherein determining the parking stall identifier comprises: capturingone or more images of the occupied parking stall using an image detectormounted on the patrol vehicle; and processing the one or more images toidentify the parking stall identifier.
 12. The method of claim 11,wherein processing the one or more images comprises converting the oneor more images into a machine-encoded text.
 13. The method of claim 7,wherein the parking stall identifier is designed to minimize blooming.14. The method of claim 7, wherein determining the parking stallidentifier comprises: scanning the occupied parking stall using aradio-frequency identification reader mounted on the patrol vehicle,wherein the parking stall identifier comprises a radio-frequencyidentification tag detectable by the radio-frequency identificationreader.
 15. The method of claim 7, wherein determining the parking stallidentifier comprises identifying the GPS coordinates corresponding tothe occupied parking stall being patrolled and determining an associatedparking stall identifier by querying a parking management database. 16.The method of claim 7, wherein identifying an occupied parking stall inthe parking lot comprises: scanning each parking stall within theparking lot to capture one or more images of the parking stall; andprocessing the one or more images to detect absence or presence of avehicle in the parking stall.
 17. The method of claim 9, whereindetermining the detected vehicle identifier comprises: detecting alicense plate number of the parked vehicle using an image detector. 18.A parking lot management system for a parking lot comprising a pluralityof parking stalls for occupancy by a plurality of vehicles, each parkingstall being uniquely identifiable using a parking stall identifier, thesystem comprising: a communication network; a non-transient computermemory; and at least processor coupled to the non-transient computermemory and the communication network, the at least one processor beingconfigured to: i. receive a parking authorization request from a parkinglot user, the parking authorization request specifying a parking stallidentifier corresponding to a parking stall that is occupied by avehicle belonging to the parking lot user, the parking authorizationrequest further specifying a parking duration parameter identifying aduration of time for which the parking lot user can park the vehicle atthe parking stall; ii. determine a parking duration rule for the parkingstall based on the parking duration parameter, the parking duration ruleindicating a parking expiration time at which the vehicle must vacate;iii. at a first time, receive a first data associated with the parkingstall identifier, the first data comprising an occupancy parameterindicating a presence or an absence of a parked vehicle at the parkingstall identified by the parking stall identifier; iv. if the occupancyparameter indicates a presence of a parked vehicle, determine if thefirst time exceeds the parking expiration time; and v. if the first timeexceeds the parking expiration time, generate a citation alert for theparking stall identified by the parking stall identifier.
 19. Theparking lot management system of claim 18, wherein the processor isfurther configured to perform the method as defined in any one of claims2 to
 17. 20. A computer-readable medium storing computer-executableinstructions, the instructions for causing at least one processor toperform a method of managing a parking area, the parking area comprisinga plurality of parking stalls for occupancy by a plurality of vehicles,each parking stall being uniquely identifiable using a parking stallidentifier, the method comprising: receiving a parking authorizationrequest from a parking lot user, the parking authorization requestspecifying a parking stall identifier corresponding to a parking stallthat is occupied by a vehicle belonging to the parking lot user, theparking authorization request further specifying a parking durationparameter identifying a duration of time for which the parking lot usercan park the vehicle at the parking stall; determining a parkingduration rule for the parking stall based on the parking durationparameter, the parking duration rule indicating a parking expirationtime at which the vehicle must vacate; at a first time, receiving afirst data associated with the parking stall identifier, the first datacomprising an occupancy parameter indicating a presence or an absence ofa parked vehicle at the parking stall identified by the parking stallidentifier; if the occupancy parameter indicates a presence of a parkedvehicle, determining if the first time exceeds the parking expirationtime; and if the first time exceeds the parking expiration time,generating a citation alert for the parking stall identified by theparking stall identifier.